Method to produce a protective oxide on the surface of positive nickel electrodes for galvanic cells

DETAILED DESCRIPTION We claim: 1.
The method for the production of a thin protective layer of nickel oxide on the surface of a porous nickel electrode for use in a galvanic cell comprising contacting the nickel electrode to a chemical or electro-chemical processing to form a film of 5-30 molecular layers thickness of nickel hydroxide thereon, contacting said electrode with an oxygen containing atmosphere to decompose the nickel hydroxide layer to the desired nickel oxide, contacting the nickel electrode with an oxygen containing atmosphere at a temperature in the range of 160.
degree.
-400.
degree.
C and for a period of time of at least half an hour and thereafter recovering a nickel electrode having a thin protective film of nickel oxide on the surface thereof.
2.
The method in accordance with claim 1, wherein the atmosphere is air.
3.
The method in accordance with claim 1 wherein the atmosphere is substantially pure oxygen.
4.
The method in accordance with claim 1, wherein the atmosphere is substantially pure oxygen and the temperature employed is in the range 160.
degree.
-220.
degree.
C and said contacting is carried out in the presence of a silver containing catalyst.




Description:
For the positive electrode of fuel cells, electolyzers, and accumulators with alkaline electrolytes a porous Ni-structure is necessary, in which the active mass of accumulators or the catalyzer of electrolyzers or fuel cells is embedded.
This porous Ni-structure is preferably produced from carbonyl-nickel by sinter-operation or heat-pressure.
At ambient temperatures, this carbonyl-nickel structure meets the required conditions at the best; at higher temperatures of about 40.
degree.
-100.
degree.
C, however, Ni begins to oxidize and develops voluminous Ni-hydroxide.
This developing of hydroxide occurs only on the surface of the Ni-structure, thus, the electrical conductivity is not considerably changed by this oxidation; whereas, the porosity of the Ni-structure is strongly reduced by this process because the specific volume of Ni(OH)